Vintage swimwear: Stunning 1940s Cole of California advert

Isn’t this wonderful? The illustration is just gorgeous, but is this the vintage swimwear in this Cole of California advert actually a swimsuit or a bikini? I’m not sure.

The text reads: 

Streamline – beautiful new backsweep… in a Lastex swimsuit… from Cole’s “Westward to the Sea” beachwear collection. 

So no clues there! The ad is taken from ‘The Californian’ magazine from February 1947, which seems a bit early for a bikini. Any ideas?